1. Field of the Invention
The present invention relates to a technique in which a plurality of digital signals to be tested are processed.
2. Description of the Related Art
In a test of a semiconductor device provided with an analogue circuit, analogue signals output from a device to be tested are converted into digital signals by an analogue-digital converter (hereinafter sometimes referred to as “ADC”), and the digital signals are analyzed, so as to determine whether the device is good or not. For example, Patent Document 1 discloses a test apparatus for testing large-scale ICs (LSIs) which transmits/receives both digital and analogue signals. The test apparatus is composed of a plurality of sub-systems. In the test apparatus, a waveform digitizer sub-system (WD-SS) is provided with a DSP which performs a desired calculation on digital signals digitized by an ADC.
Parent Document 1: Japanese Patent Publication Laid-open No. Hei 4-36671.
As communication apparatuses have been widely in use, communication devices have been actively developed and produced, therefore, it is strongly requested to perform tests for such devices effectively. For example, in a modulation device for transmitting signals, I component (in-phase component) baseband modulated signal and Q component (orthogonal component) baseband modulated signal are generated. It is preferable that a test apparatus can test two types of signals in a shorter time and effectively. Further, in an analogue test, a determination may be made as to whether a device is good or not, by referring to the mutual relations between multiple types of signals output from the analogue circuit. Therefore, a technique which can effectively test multiple types of signals is strongly desired.